1. Field of the Invention
This invention relates to the field of structured light and specifically to the provision of a structured light source for use in providing stereoscopic images which require no special eye wear to be worn by the observer. Such images are usually described as autostereoscopic.
2. Description of Related Art
In U.S. Pat. No. 5,936,774 (Street), which is incorporated by reference herein, a single LCD screen provides both images for an autostereoscopic image pair. This is made possible by a structured light source. The light source is structured by the incorporation of two lenticular screens, each with its cylindrical lens elements running substantially orthogonal to those of the other, in combination with a single, patterned, typically chequered, mask and a standard back light. This arrangement causes at least a particular spectral range of the light from alternate rows of elements within the array of picture elements comprising the LCD image to reach substantially only one eye of the observer and the equivalent light from the other lines of picture elements to reach substantially only the observer's other eye. Such an arrangement is intrinsically inefficient in preserving the light from the back light when the patterned mask is a blocking array, and/or is separated from the back light for structural reasons (for example due to the motion requirement for observer tracking).